Trina Rocker was arrested in September 2012 following an investigation by the Polk County Sheriff's Office.

The 42-year-old Haines City woman had sexual encounters with the boy on five occasions at places ranging from her Cadillac to a shed outside her home as well as inside a hotel laundry room during a senior trip to Washington, D.C., according to investigative reports.

A jury was prepared Tuesday to begin hearing testimony in Rocker's case.

But instead of going to trial, she pleaded guilty to three counts of unlawful sexual activity with a minor.

Each is a second-degree felony punishable by up to 15 years in prison.

Without a plea deal in place, Rocker faces a maximum punishment of 45 years in prison. A score sheet prepared for her case calculates her lowest sentence to be about 17 years in prison.

However, Circuit Judge Dennis Maloney could impose a lower sentence but would have to provide a written explanation if he chose to do so.

A sentencing hearing is set for March 7.

Investigative reports state the boy was a student at the high school, and also knew Rocker because he was a friend of Rocker's son and daughter.

The boy's father told investigators that he discovered his son was having sex with Rocker in late 2011 or early 2012, reports state.

The father told investigators that he warned Rocker to stay away from his son but did not report the sexual relationship because he did not want to risk his son being expelled from the school “if he revealed the relationship due to Landmark Christian School's moral code,” reports state.

The boy's mother contacted authorities in September 2012 when she learned of her son's sexual relationship with Rocker, reports state.